Semiconductor laser, light emitting assembly and optical module

Abstract

The embodiment of the invention relates to a semiconductor laser, a light emitting assembly and an optical module. The semiconductor laser comprises a resonant cavity structure, the resonant cavity structure comprises a resonant cavity, the resonant cavity is used for generating standing waves, and the resonant cavity is limited by a bottom reflector structure and a top reflector structure; a multi-quantum well structure is arranged in the resonant cavity, and the multi-quantum well structure is arranged at the wave crest position of the resonant cavity; the thickness of the resonant cavity is designed to be smaller than three-second lasing wavelength so as to improve the relaxation oscillation frequency of the semiconductor laser. By applying the scheme of the invention, the relaxation oscillation frequency can be improved, and the modulation bandwidth of the device is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of semiconductor lasers, and in particular, to a surface-emitting laser. Background Art

[0002] Currently, data centers have become the basic carriers of new communication networks such as 5G and the Internet of Things, as well as fields such as the Internet, cloud computing, and artificial intelligence, carrying 99% of the world's data traffic. It is the supporting technology for China to realize innovative applications such as industrial Internet, enterprise cloud adoption, and edge computing, as well as digital transformation in the future. With the rapid popularization and application of new technologies such as 5G, artificial intelligence (AI), the Internet of Things, and VR / AR, the explosive growth of data traffic has continuously increased the requirement for bandwidth. The Ethernet speed has advanced from 400 GbE to 800 GbE, and it is expected to break through the 1 TbE technical barrier by 2025, driving the generational change of data centers. Optical interconnection based on 850 nm semiconductor lasers (VCSELs) has become the standard solution for short-distance data transmission between rooms, racks, and boards within data centers due to its advantages such as high transmission rate, low power consumption, and strong anti-interference ability.

[0003] VCSELs have become the preferred light sources for short-distance optical interconnection due to their advantages such as high modulation speed, easy coupling with optical fibers, and low power consumption. It is the most critical technology determining the single-channel rate of optical modules. The core difficulty in improving its transmission rate lies in how to obtain a synergistic solution among the mutually restrictive factors such as reliability, high differential gain required for rate improvement, low carrier transport factor, precise matching of microcavity damping, and thermal effect management. Summary of the Invention

[0004] Based on this, it is necessary to provide a semiconductor laser, an optical emission component, and an optical module for the above technical problems.

[0005] In a first aspect, the present application provides a semiconductor laser, including a resonant cavity structure. The resonant cavity structure includes a resonant cavity for generating a standing wave, and the resonant cavity is defined by a bottom mirror structure and a top mirror structure. A multi-quantum well structure is provided in the resonant cavity, and the multi-quantum well structure is disposed at the peak position of the resonant cavity. The thickness of the resonant cavity is designed to be less than three halves of the lasing wavelength to increase the relaxation oscillation frequency of the semiconductor laser.

[0006] In one embodiment, the thickness of the resonant cavity is between one lasing wavelength and three halves of the lasing wavelength; or the thickness of the resonant cavity is between one half of the lasing wavelength and one lasing wavelength; or the thickness of the resonant cavity is less than or equal to one half of the lasing wavelength.

[0007] In one embodiment, the multi-quantum well structure includes a plurality of overlapping well layers and barrier layers, and the strain modes and / or strain amounts of the well layers and the barrier layers are not completely the same.

[0008] In one embodiment, the strain modes of at least some adjacent well layers and barrier layers are different; or the strain modes of at least some adjacent well layers and barrier layers are the same.

[0009] In one embodiment, the strain amounts of at least some adjacent well layers and barrier layers are different; or the strain amounts of at least some adjacent well layers and barrier layers are the same.

[0010] In one embodiment, along the direction close to the top mirror structure, the strain amount of at least some well layers changes stepwise; or the strain amount of at least some barrier layers changes stepwise.

[0011] In one embodiment, along the direction close to the top mirror structure, the strain amount of at least some well layers changes in an arithmetic progression; or the strain amount of at least some barrier layers changes in an arithmetic progression.

[0012] In one embodiment, along the direction close to the top mirror structure, the strain amount of at least some well layers changes in a geometric progression; or the strain amount of at least some barrier layers changes in a geometric progression.

[0013] In one embodiment, along the direction close to the top mirror structure, the strain modes of at least some well layers are the same; or the strain modes of at least some barrier layers are the same.

[0014] In one embodiment, the strain mode includes any one of compressive strain, tensile strain, and no strain.

[0015] In one embodiment, the strain amount is between 0.03% and 12%.

[0016] In one embodiment, the multi-quantum well structure includes a plurality of overlapping well layers and barrier layers. At least one well layer in the well layers is a compressive strain well layer, and the indium component content in the compressive strain well layer is 0.12.

[0017] In one embodiment, the well layers and the barrier layers are made of InGaAs and AlGaAs materials respectively.

[0018] In one embodiment, it further includes: An oxide confinement layer formed in the top mirror structure, the oxide confinement layer being disposed adjacent to the resonant cavity, and the oxide confinement layer being used to define the light-emitting region of the semiconductor laser.

[0019] The present application provides a semiconductor laser, including a resonant cavity structure, the resonant cavity structure including a resonant cavity for generating a standing wave, the resonant cavity being defined by a bottom mirror structure and a top mirror structure; a multiple quantum well structure is disposed in the resonant cavity, and the multiple quantum well is disposed at the peak position of the resonant cavity; the thickness of the resonant cavity is designed to be less than three halves of the lasing wavelength, that is to say, the present application adopts a method of reducing the photon volume (designing the cavity length of the resonant cavity to be less than three halves of the lasing wavelength) in the epitaxial design, and disposes the multiple quantum well structure at the peak position in the microcavity to obtain a larger optical confinement factor, thereby increasing the relaxation oscillation frequency.

[0020] In a second aspect, the present application provides an optical emission component, the optical emission component including the semiconductor laser described above.

[0021] In a third aspect, the present application provides an optical module, including an optical emission module and an optical reception module, and the optical emission module employs the optical emission component described above. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of a semiconductor laser in an embodiment of the present application; Figures 2a-2e is Figure 1 a schematic diagram of the arrangement of different well-barrier layers in an embodiment; Figure 3 is a schematic diagram of the optical field intensity distribution in the resonant cavity in an embodiment of the present application; Figure 4 is a schematic structural diagram of a semiconductor laser in another embodiment of the present application.

[0023] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the drawings. Detailed Embodiments

[0024] In order to make the object, technical solution and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] It can be understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, the first client may be referred to as the second client, and similarly, the second client may be referred to as the first client.

[0026] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. The meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined. The meaning of "several" is at least one, such as one, two, etc., unless otherwise specifically defined.

[0027] As described in the background art of this application, currently, data centers have become the basic carriers of new communication networks such as 5G and the Internet of Things, as well as fields such as the Internet, cloud computing, and artificial intelligence, carrying 99% of the global data traffic. They are the supporting technologies for China's future implementation of innovative applications such as industrial Internet, enterprise cloud adoption, and edge computing, as well as digital transformation. With the rapid popularization and application of new technologies such as 5G, artificial intelligence (AI), the Internet of Things, and VR / AR, the explosive growth of data traffic has continuously increased the demand for bandwidth. The Ethernet speed has advanced from 400 GbE to 800 GbE, and it is expected to break through the 1 TbE technical barrier by 2025, driving the generational change of data centers. Optical interconnection based on 850 nm semiconductor lasers (VCSELs) has become the standard solution for short-distance data transmission between machine rooms, racks, and boards within data centers due to its advantages such as high transmission rate, low power consumption, and strong anti-interference ability.

[0028] VCSEL (Vertical-Cavity Surface-Emitting Laser) has become the preferred light source for short-distance optical interconnection due to its advantages such as high modulation speed, easy coupling with optical fibers, and low power consumption. It is the most critical technology determining the single-channel rate of optical modules. The core difficulty in improving its transmission rate lies in obtaining a synergistic solution among factors that restrict each other, such as reliability, high differential gain required for rate improvement, low carrier transport factor, precise matching of microcavity damping, and thermal effect management.

[0029] Based on this, reference can be made to Figures 1-4。This application provides a semiconductor laser, which can be, for example, a vertical-cavity surface-emitting laser (VCSEL) or an edge-emitting laser (EEL) of a semiconductor laser. This application takes the semiconductor laser VCSEL as an example for illustration. The semiconductor laser may include a resonant cavity structure (not shown in the figure), and the resonant cavity structure includes a resonant cavity for generating a standing wave, and the resonant cavity is defined by a bottom mirror structure 110 and a top mirror structure 130. Specifically, the bottom mirror structure 110 and the top mirror structure 130 define the resonant cavity structure of the semiconductor laser of this application, that is, the region between the bottom mirror structure 110 and the top mirror structure 130 is the resonant cavity. The resonant cavity is used to generate a standing wave, and a standing wave is a wave formed by two coherent waves propagating in opposite directions on the same straight line and superimposing on each other. Specifically, when the phases of the two waves are the same, their amplitudes are added to form a wave crest (i.e., a wave peak). When the phases of the two waves are opposite, their amplitudes are subtracted to form a node (i.e., a wave trough). Therefore, the positions of the wave peaks and wave troughs of the standing wave are fixed.

[0030] A multi-quantum well structure 120 is disposed in the resonant cavity, and the multi-quantum well structure 120 is disposed at the wave peak position of the resonant cavity. Specifically, the multi-quantum well structure 120 is used to generate photons of stimulated emission, and the emitted photons are continuously reflected in the resonant cavity defined by the bottom mirror structure 110 and the top mirror structure 130 and continuously enhanced during the reflection process, so as to finally emit laser light at a specific wavelength and with sufficient energy.

[0031] The multi-quantum well structure 120 is a place where laser gain amplification occurs. The central position of the multi-quantum well structure 120 can be aligned with the position where the optical field is the strongest (i.e., the wave peak position of the resonant cavity) to achieve a greater amplification effect. Further, the number of the multi-quantum well structures 120 can be multiple. In the case of including multiple multi-quantum well structures 120, the confinement factors of the multi-quantum well structures 120 in the same optical field are within the same preset range, that is, the confinement factors of each multi-quantum well structure 120 are maintained at the same level, so that the contribution of each multi-quantum well structure 120 to light emission is similar. It can be understood that similar light emission contributions mean that the current injection in each multi-quantum well structure 120 is more uniform, which helps to reduce the threshold current of the device, thereby reducing the power consumption of the device and prolonging its service life. Moreover, when the contribution of each multi-quantum well structure 120 to light emission is similar, the distribution of carriers in each multi-quantum well structure 120 will be more uniform, which helps to reduce the recombination loss of carriers, thereby improving the overall light emission efficiency of the device.

[0032] The inventors of the present application have found through research that the intrinsic modulation bandwidth of a laser increases with the increase in the relaxation oscillation frequency, and the relaxation oscillation frequency is closely related to factors such as the differential gain of the quantum well and the photon volume in the cavity. A larger relaxation oscillation frequency requires a high differential gain and a small photon volume. For reference, Figure 3 , the thickness of a traditional resonant cavity is generally designed to be three - halves of the lasing wavelength, but the photon volume at this thickness is still relatively large, and the effect on enhancing the intrinsic modulation bandwidth is not significant enough. Therefore, the present application first improves the relaxation oscillation frequency of a semiconductor laser by reducing the photon volume, and then enhances the intrinsic modulation bandwidth of the semiconductor laser; specifically, the thickness of the resonant cavity is designed to be less than three - halves of the lasing wavelength. Further, the thickness of the resonant cavity is designed to be between one lasing wavelength and three - halves of the lasing wavelength, excluding three - halves of the lasing wavelength; for example, the thickness of the resonant cavity is designed to be one lasing wavelength, i.e., λ, or the thickness of the resonant cavity is designed to be four - thirds of the lasing wavelength, i.e., 4 / 3λ; or, the thickness of the resonant cavity is between one - half of the lasing wavelength and one lasing wavelength, excluding one lasing wavelength; for example, the thickness of the resonant cavity is designed to be greater than one - half of the lasing wavelength, i.e., 1 / 2λ (excluding one - half of the lasing wavelength), or the thickness of the resonant cavity is designed to be three - fifths of the lasing wavelength, i.e., 3 / 5λ, or the thickness of the resonant cavity is designed to be seven - tenths of the lasing wavelength, i.e., 7 / 10λ, or the thickness of the resonant cavity is designed to be four - fifths of the lasing wavelength, i.e., 4 / 5λ; or the thickness of the resonant cavity is less than or equal to one - half of the lasing wavelength, for example, the thickness of the resonant cavity is equal to one - half of the lasing wavelength, i.e., 1 / 2λ, or the thickness of the resonant cavity is equal to two - fifths of the lasing wavelength, i.e., 2 / 5λ, etc. The present application will not elaborate further on this, Figure 3 shows the case where the thickness of the resonant cavity is set to one - half of the lasing wavelength, i.e., 1 / 2λ. In theory, a smaller photon volume is more beneficial for enhancing the relaxation oscillation frequency.

[0033] Further, the bottom mirror structure 110 may include a periodically stacked DBR structure, that is, it includes multiple mirrors with an optical thickness of one-quarter of the lasing wavelength, and the multiple mirrors are alternately arranged according to high and low refractive indices. The top mirror structure 130 also includes a periodically stacked DBR structure, that is, multiple mirrors with an optical thickness of one-quarter of the lasing wavelength, and the multiple mirrors are alternately arranged according to high and low refractive indices. It can be understood that the components, number of stacking periods, etc. of the DBR structure of the bottom mirror structure 110 and the DBR structure of the top mirror structure 130 may be the same or different, which is not limited in this embodiment. Among them, the materials of the top mirror structure 130 and the bottom mirror structure 110 may be dielectric materials with electrical insulation properties, such as silicon nitride, silicon oxide, aluminum oxide, or titanium oxide, etc. The materials of the top mirror structure 130 and the bottom mirror structure 110 may also be semiconductor materials, such as GaAs and AlGaAs.

[0034] In one embodiment, the foregoing semiconductor laser may further include a substrate 10 ( Figure 4 ), the bottom mirror structure 110 is epitaxially grown on the substrate 10, and the material of the substrate 10 includes but is not limited to GaAs, InP, Si, etc. The bottom mirror structure 110 and the top mirror structure 130 may include film layers with periodically varying refractive indices to achieve efficient reflection or transmission of light within a specific wavelength range. The film layers with periodically varying refractive indices may be composed of semiconductor materials, dielectric materials, metal-dielectric hybrid materials, etc. For example, the bottom mirror structure 110 may be an N-type semiconductor layer, and the top mirror structure 130 may be a P-type semiconductor layer. Another example is that the bottom mirror structure 110 may be a P-type semiconductor layer, and the top mirror structure 130 may be an N-type semiconductor layer. Optionally, the materials of the N-type semiconductor layer and the P-type semiconductor layer may be but are not limited to GaAs, AlGaAs, etc., which is not limited here as long as the resonator can be defined, and all belong to the protection scope of this embodiment. Specifically, the resonator structure may further include an oxide confinement layer 132, and the oxide confinement layer 132 is formed in the top mirror structure 130.

[0035] In one embodiment, the aforementioned semiconductor laser may further include an oxide confinement layer 132 formed in the top mirror structure 130. The oxide confinement layer 132 is disposed adjacent to the resonant cavity and is used to define the light-emitting region of the semiconductor laser. Specifically, the oxide confinement layer 132 is located on the side of the corresponding multiple quantum well structure 120 away from the substrate 10 to restrict the flow of current, enabling the current to flow only within the light-emitting region defined by the oxide confinement layer 132, thereby reducing unnecessary energy consumption, further decreasing the threshold current, and increasing the current density. Moreover, the oxide confinement layer 132 can also confine the optical field within the light-emitting region defined by the oxide confinement layer 132, reducing light scattering and diffraction, thereby optimizing the divergence angle of the device and improving the beam quality. Generally, the oxide confinement layer 132 is disposed at the position with the lowest optical field intensity, i.e., at the trough of the standing wave, so that it has a smaller confinement factor, which helps to reduce the divergence angle of the device.

[0036] The oxide confinement layer 132 may include any one of an air column type optoelectronic confinement layer, an oxidation confinement type optoelectronic confinement layer, an ion implantation type optoelectronic confinement layer, and a tunnel junction type optoelectronic confinement layer. Among them, the air column type optoelectronic confinement layer realizes the confinement of current and light through air columns. The air columns are hollow structures formed by dry etching technology, and their refractive index is lower than that of the surrounding semiconductor material, thus effectively confining the light within the central region. The ion implantation type optoelectronic confinement layer changes the electrical properties of the semiconductor material by implanting ions to form a high-resistance region, and the high-resistance region can restrict the flow of current, thereby indirectly restricting the light generation region.

[0037] In one embodiment, the oxidation confinement type optoelectronic confinement layer includes an unoxidized region made of AlGaAs with a high Al component and an oxidized region made of aluminum oxide. The oxidized region is disposed outside the unoxidized region, and the unoxidized region forms a light-emitting region for effective current injection. Among them, the semiconductor layer of the unoxidized region in the oxide confinement layer 132 can be understood as an opening, and the opening is used to define the light-emitting area of the semiconductor laser. When the current enters, the current can only flow through the opening in the oxide confinement layer 132 to the multiple quantum well structure 120, thereby realizing the confinement of the current injection path and the optical mode field. Further, through a selective oxidation process, the AlGaAs layer with a high aluminum component can be converted into aluminum oxide to form the peripheral unoxidized region.

[0038] In one embodiment, the tunnel junction type optoelectronic confinement layer includes at least one highly doped N-type structural layer and at least one highly doped P-type structural layer. Specifically, a potential barrier is formed between the highly doped N-type structural layer and the highly doped P-type structural layer, and electrons are allowed to pass through the potential barrier through the tunnel effect, thereby realizing the lateral confinement of the current. In one embodiment, the materials of the N-type structural layer and the P-type structural layer are selected as Alx Ga 1-x As, the doping concentrations of the N-type structural layer and the P-type structural layer are greater than 1e 18 cm -3 , where 0 ≤ x ≤ 1.

[0039] In one embodiment, since the hole mobility in GaAs is much higher than that in AlGaAs, the semiconductor laser of the present application may further include a heavily doped GaAs layer, and the heavily doped GaAs layer is placed on the top mirror structure 130 as a P-type electrical contact layer.

[0040] In one embodiment, reference may be made to Figure 1 , the multi-quantum well structure 120 of the present application may include a plurality of overlapping well layers and barrier layers, and the strain modes and / or strain amounts of the well layers and the barrier layers are not completely the same. Exemplarily, the strain mode includes any one of compressive strain, tensile strain or no strain, and the strain amount ranges from 0.03% to 12%. It can be understood that the strain amount here mainly refers to tensile strain and compressive strain. For example, when the well layer is under compressive strain, the compressive strain amount of the well layer can be selected to range from 0.03% to 12%; or, when the well layer is under tensile strain, the tensile strain amount of the well layer can be selected to range from 0.03% to 12%; or, when the barrier layer is under compressive strain, the compressive strain amount of the barrier layer can be selected to range from 0.03% to 12%; or, when the barrier layer is under tensile strain, the tensile strain amount of the barrier layer can be selected to range from 0.03% to 12%. Further, the strain amount can specifically be selected to be between 0.03% and 0.05%; or, the strain amount can specifically also be selected to be between 0.05% and 1%; or, the strain amount can specifically also be selected to be between 1% and 1.5%; or, the strain amount can specifically also be selected to be between 1.5% and 2%; or, the strain amount can specifically also be selected to be between 2% and 2.5%; or, the strain amount can specifically also be selected to be between 2.5% and 3%; or, the strain amount can specifically also be selected to be between 3.5% and 4%; or, the strain amount can specifically also be selected to be between 4.5% and 5%; or, the strain amount can specifically also be selected to be between 5.5% and 6%; or, the strain amount can specifically also be selected to be between 6.5% and 7%; or, the strain amount can specifically also be selected to be between 7.5% and 8%; or, the strain amount can specifically also be selected to be between 8.5% and 9%; or, the strain amount can specifically also be selected to be between 9.5% and 10%; or, the strain amount can specifically also be selected to be between 10.5% and 11%; or, the strain amount can specifically also be selected to be between 11.5% and 12%. The above are only examples and should not be construed as a limitation to the present application.

[0041] In one embodiment, the strain modes of at least some adjacent well layers and barrier layers are different (such as Figure 2a ,Figure 2b , Figure 2c , Figure 2d and Figure 2e ), for example, some adjacent well layers and barrier layers are compressively strained well layers and tensile strained barrier layers respectively, or vice versa; or at least some adjacent well layers and barrier layers have the same strain mode (such as Figure 2a , Figure 2b , Figure 2d ), for example, some adjacent well layers and barrier layers are all compressively strained well layers and barrier layers, or some adjacent well layers and barrier layers are all tensile strained well layers and barrier layers. By setting the strain modes of at least some adjacent well layers and barrier layers to be the same or different, compared with all being of one strain mode, for example, all using tensile strained well layers and tensile strained barrier layers for stacking, such a stacking method will cause the strain amount to accumulate. If the number of stacked tensile strained well layers and tensile strained barrier layers is too large, it will lead to an excessive tensile strain amount in the multiple quantum well structure 120, resulting in dislocations in the material of the multiple quantum well structure 120, affecting the performance of the semiconductor laser, and even causing the semiconductor optoelectronic device to malfunction. In addition, by setting the strain modes of at least some adjacent well layers and barrier layers to be the same or different, effective stress compensation and release can be carried out between the tensile strain and the compressive strain. While introducing a certain amount of compressive strain to increase the relaxation oscillation frequency of the device, the generation of defects due to stress accumulation can be avoided, and the reliability of the semiconductor laser can be improved.

[0042] In one embodiment, the strain amounts of at least some adjacent well layers and barrier layers are different; or the strain amounts of at least some adjacent well layers and barrier layers are the same. For example, when the strain modes of some adjacent well layers and barrier layers are the same, such as all being compressively strained, the strain amounts of the adjacent compressively strained well layer and the compressively strained barrier layer can be different. For example, the compressive strain amount of one compressively strained well layer is 2%, and the compressive strain amount of the compressively strained barrier layer adjacent to this compressively strained well layer is 1%.

[0043] For another example, when the strain modes of some adjacent well layers and barrier layers are all tensile strained, the tensile strain amount of one tensile strained well layer is 2%, and the tensile strain amount of the tensile strained barrier layer adjacent to this tensile strained well layer is 1%. The larger strain amount of the tensile strained well layer causes changes in the energy band characteristics of the well layer crystal, making the light hole band on the valence band side in the tensile strained well layer rise more, so that the carrier transition mainly occurs between the conduction band and the light hole band. The effective mass of holes in the light hole band is small in the direction perpendicular to the well, and the longitudinal migration speed of light holes is relatively fast, which is beneficial to the transport of holes, and is also beneficial to the effective transition of carriers. At the same time, the hole state density is small, and it is easier to form population inversion under the same carrier injection, thereby increasing the differential gain of the active layer. The increase in the differential gain of the active layer is beneficial to improving the speed performance of the semiconductor optoelectronic device.

[0044] For another example, when the strain modes of some adjacent well layers and barrier layers are different, for example, the well layer is under compressive strain and the barrier layer is under tensile strain, the strain amounts of the adjacent compressive-strain well layer and tensile-strain barrier layer can be different. For example, the compressive strain amount of one compressive-strain well layer is 2%. The compressive strain causes the separation of the light-hole and heavy-hole energy bands, resulting in a significant reduction in the heavy-hole mass component parallel to the interface, thereby causing a reduction in the hole state density and a significant increase in the differential gain of the quantum well. While the compressive strain amount of the tensile-strain barrier layer adjacent to this compressive-strain well layer is 3%. By making the strain amount of the tensile-strain barrier layer slightly larger than that of the compressive-strain well layer, the well region on the valence band side can be shallower, thereby controlling the number of bound states in the well layer on the valence band side. In addition, the tensile-strain barrier layer is conducive to the capture of valence-band holes in the barrier layer and can shorten the transit time of valence-band holes in the barrier layer, which is beneficial to the transport of holes between the barrier layer and the well layer and improves the alternating current (AC) characteristics of the semiconductor laser. Further, when at least one well layer in the well layers is a compressive-strain well layer, the indium component content in the compressive-strain well layer can be 0.12. In this specific embodiment, the well layer and the barrier layer can be made of InGaAs and AlGaAs materials respectively. Using a compressive-strain InGaAs / AlGaAs quantum well with a large In component as the active region, the compressive strain causes the separation of the light-hole and heavy-hole energy bands, resulting in a significant reduction in the heavy-hole mass component parallel to the interface, thereby causing a reduction in the hole state density and a significant increase in the differential gain of the quantum well to obtain a large relaxation oscillation frequency.

[0045] For another example, when the strain modes of some adjacent well layers and barrier layers are different, for example, the well layer is under tensile strain and the barrier layer is under compressive strain, the strain amounts of the adjacent tensile-strain well layer and compressive-strain barrier layer can be different. For example, the tensile strain amount of one tensile-strain well layer is 2%, and the compressive strain amount of the adjacent compressive-strain barrier layer is 3%, or vice versa.

[0046] For another example, based on the case where the strain modes are the same or different as described above, when the strain amounts between the adjacent barrier layer and well layer are the same, for example, both are 2%. The same strain amount can effectively compensate for and release the stress of the multi-quantum well structure 120 and improve the gain of the multi-quantum well structure 120. The specific description of this method can be understood with reference to the foregoing embodiments, and the present application will not elaborate on this.

[0047] In one embodiment, along the direction close to the top mirror structure 130, the strain of at least part of the well layers changes stepwise; or the strain of at least part of the barrier layers changes stepwise. In this specific embodiment, the case where the strain of part of the well layers changes stepwise can be based on the same strain modes of these well layers. For example, they are all compressive strain modes, or all tensile strain modes; or the strain modes of these well layers are different. For example, there are both compressive strain modes and tensile strain modes, where the strain of the well layer closest to the top mirror structure 130 is the largest or the smallest, that is, increasing stepwise or decreasing stepwise. Similarly, the case where the strain of part of the barrier layers changes stepwise can be based on the same strain modes of these barrier layers. For example, they are all compressive strain modes, or all tensile strain modes; or the strain modes of these barrier layers are different. For example, there are both compressive strain modes and tensile strain modes, where the strain of the barrier layer closest to the top mirror structure 130 is the largest or the smallest, that is, increasing stepwise or decreasing stepwise. Controlling the strain to change stepwise can make the stress distribution more uniform and avoid the generation of more defects.

[0048] In one embodiment, along the direction close to the top mirror structure 130, the strain of at least part of the well layers changes in an arithmetic progression; or the strain of at least part of the barrier layers changes in an arithmetic progression. In this specific embodiment, the case where the strain of part of the well layers changes in an arithmetic progression can be based on the same strain modes of these well layers. For example, they are all compressive strain modes, or all tensile strain modes; or the strain modes of these well layers are different. For example, there are both compressive strain modes and tensile strain modes, where the strain of the well layer closest to the top mirror structure 130 is the largest or the smallest, that is, increasing in an arithmetic progression or decreasing in an arithmetic progression. Similarly, the case where the strain of part of the barrier layers changes in an arithmetic progression can be based on the same strain modes of these barrier layers. For example, they are all compressive strain modes, or all tensile strain modes; or the strain modes of these barrier layers are different. For example, there are both compressive strain modes and tensile strain modes, where the strain of the barrier layer closest to the top mirror structure 130 is the largest or the smallest, that is, increasing in an arithmetic progression or decreasing in an arithmetic progression. Controlling the strain to change in an arithmetic progression can make the stress distribution more uniform and avoid the generation of more defects.

[0049] In one embodiment, along the direction close to the top mirror structure, the strain of at least part of the well layers changes in a geometric progression; or the strain of at least part of the barrier layers changes in a geometric progression. In this specific embodiment, the case where the strain of part of the well layers changes in a geometric progression can be based on the same strain modes of these well layers, for example, all are compressive strain modes, or all are tensile strain modes; or the strain modes of these well layers are different, for example, there are both compressive strain modes and tensile strain modes, and the strain of the well layer closest to the top mirror structure 130 is the largest or the smallest, that is, it increases or decreases in a geometric progression. Similarly, the case where the strain of part of the barrier layers changes in a geometric progression can be based on the same strain modes of these barrier layers, for example, all are compressive strain modes, or all are tensile strain modes; or the strain modes of these barrier layers are different, for example, there are both compressive strain modes and tensile strain modes, and the strain of the barrier layer closest to the top mirror structure 130 is the largest or the smallest, that is, it increases or decreases in a geometric progression. Controlling the strain to change in a geometric progression can make the stress distribution more uniform and avoid the generation of more defects.

[0050] In one embodiment, along the direction close to the top mirror structure, the strain modes of at least part of the well layers are the same; or the strain modes of at least part of the barrier layers are the same. The strain modes of at least part of the well layers are the same (such as Figure 2a , Figure 2b , Figure 2c , Figure 2d and Figure 2e ), for example, some of the well layers are all compressive-strained well layers, or all tensile-strained well layers, or vice versa; or some of the barrier layers are all compressive-strained barrier layers, or all tensile-strained barrier layers, or vice versa. This embodiment does not require that the strain modes and strains of the well layers and barrier layers must be the same; by setting the strain modes of at least part of the well layers to be the same or the strain modes of the barrier layers to be the same, compared with all being of one strain mode, for example, all using tensile-strained well layers and tensile-strained barrier layers for stacking, such a stacking method will cause the strain to accumulate. If all are of one strain mode, it will cause the strain of the multiple quantum well structure 120 to be too large, resulting in dislocations in the material of the multiple quantum well structure 120, affecting the performance of the semiconductor laser, and even causing the semiconductor optoelectronic device to fail to work properly. In addition, by controlling the strain modes and strains of part of the well layers and barrier layers, effective stress compensation and release can be carried out between the tensile strain and compressive strain in the multiple quantum well structure 120. While introducing a certain amount of compressive strain to increase the relaxation oscillation frequency of the device, the generation of defects due to stress accumulation can be avoided, and the reliability of the semiconductor laser can be improved.

[0051] Such as Figure 4As shown, the semiconductor laser further includes a dielectric layer 140 formed on the top mirror structure 130; the dielectric layer 140 is a layer that at least partially insulates the top metal 150 from one or more other layers or features (e.g., the sidewalls of the trench). Further, the dielectric layer 140 can be used to protect the top mirror structure 130. In some embodiments, the dielectric layer 140 can include, for example, silicon nitride (SiNX), silicon dioxide (SiO2), a polymer dielectric, or another type of insulating material. In some embodiments, the thickness t of the dielectric layer 140 can be in the range from about 0.92×(λ / nd) to about 1.45×(λ / nd), where λ is the wavelength of the vertical-cavity surface-emitting laser and nd is the refractive index of the dielectric material. More generally, the thickness T of the dielectric layer 140 can be equal to the thickness t plus or minus a value that corresponds to a multiple of the wavelength of the semiconductor laser divided by twice the refractive index of the dielectric material (e.g., T = t ± X×λ / (2*nd), where 0.92×(λ / nd) ≤ t ≤ 1.45×(λ / nd), and X is an integer value such as 0, 1, 2, etc.). In some embodiments, the thickness T of the dielectric layer 140 can vary by some amount (e.g., ±10 nm, ±15 nm) according to the VCSEL design. Thus, in some embodiments, the thickness of the dielectric layer 140 is within a value of about 15 nm, which is equal to the value within the range from about 0.92×(λ / nd) to about 1.45×(λ / nd) plus or minus the value equal to X×λ / (2*nd), where λ is the wavelength of the VCSEL, nd is the refractive index of the dielectric material, and X is an integer value.

[0052] Figure 4 In addition, the semiconductor laser can further include a top metal 150, which is a top metal layer at the front side of the semiconductor laser. In some embodiments, the top metal 150 can be a layer that is in direct contact with the heavily doped P-type electrical contact GaAs layer (e.g., through a via penetrating the dielectric layer 140), or can be a layer that is in direct contact with an ohmic contact metal layer (not shown in the figure) provided on the heavily doped P-type electrical contact GaAs layer. In some embodiments, the top metal 150 can be used as the anode for the semiconductor laser. In some embodiments, the top metal 150 can include an electroplated metal (e.g., gold (Au)) and / or a seed metal used in the electroplating process.

[0053] Figure 4In addition, the semiconductor laser may further include a bottom metal 160, which is a bottom metal layer at the rear side of the semiconductor laser. In some embodiments, the bottom metal 160 may be a layer that is in surface electrical contact with the substrate 10. In some embodiments, the top metal 150 may be used as the cathode for the semiconductor laser. In some embodiments, the top metal 150 may include an electroplated metal (e.g., gold (Au)) and / or a seed metal used in the electroplating process.

[0054] Figure 4 In addition, the semiconductor laser may further include a proton implantation region 170, which is a region that prevents free carriers from reaching the edge of the trench and / or isolates adjacent semiconductor lasers from each other (e.g., if the trench does not completely surround the semiconductor laser). The proton implantation region 170 may include, for example, an ion implantation material, such as a hydrogen / proton implantation material or a similar implantation element, to reduce the conductivity.

[0055] Figure 4 The number, arrangement, thickness, order, symmetry, etc. of the layers shown are provided as examples. In practice, compared with the Figure 4 layers shown, the semiconductor laser may include additional layers, fewer layers, different layers, layers with different structures, or layers with different arrangements. For example, in some embodiments, the semiconductor laser may include a semiconductor layer (e.g., one or more p-type layers) above the top mirror structure 130 (e.g., instead of the dielectric layer 140). As another example, in some embodiments, the semiconductor laser may include an air interface above the top mirror structure 130 (e.g., instead of the dielectric layer 140 and the top metal 150). Additionally or alternatively, a set of layers (e.g., one or more layers) of the semiconductor laser may perform one or more functions described as being performed by another set of layers of the semiconductor laser, and any layer may include more than one layer.

[0056] In summary, the present application provides a semiconductor laser, including a resonant cavity structure, the resonant cavity structure including a resonant cavity for generating a standing wave, the resonant cavity being defined by a bottom mirror structure and a top mirror structure; a multi-quantum well structure is disposed in the resonant cavity, and the multi-quantum well is disposed at the peak position of the resonant cavity; the thickness of the resonant cavity is designed to be less than three-halves of the lasing wavelength. That is to say, the present application adopts a method of reducing the photon volume (designing the cavity length of the resonant cavity to be less than three-halves of the lasing wavelength) in the epitaxial design, and disposes the multi-quantum well structure at the peak position in the microcavity to obtain a larger optical confinement factor, thereby increasing the relaxation oscillation frequency.

[0057] In a second aspect, the present application further provides an optical emission component, which includes the semiconductor laser as described in any one of the foregoing. The optical emission component in this specific embodiment may be a TOSA (Transmitting Optical Sub-Assembley), which mainly completes the conversion of electrical signals into optical signals. Among them, the light source (semiconductor light-emitting diode or laser diode) is the core, and the LD chip, the monitoring photodiode (MD) and other components are packaged in a compact structure (TO coaxial package or butterfly package).

[0058] In a third aspect, the present application further provides an optical module, which includes an optical emission module and an optical reception module, and the optical emission module uses the optical emission component as described above. The optical reception module in this specific embodiment, also known as ROSA (ResceivingOptical Sub-Assembley), is usually composed of a PIN or ADP photodiode and a TIA assembled in a sealed metal housing in a high-data-rate optical fiber module.

[0059] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0060] The above-described embodiments only represent several implementation manners of the embodiments of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the embodiments of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the embodiments of the present application. Therefore, the protection scope of the patent of the embodiments of the present application shall be subject to the appended claims.

Claims

1. A semiconductor laser, characterized in that, Comprising a resonant cavity structure, the resonant cavity structure includes a resonant cavity for generating a standing wave, and the resonant cavity is defined by a bottom mirror structure and a top mirror structure; A multi-quantum well structure is disposed in the resonant cavity, and the multi-quantum well structure is disposed at the peak position of the resonant cavity; The thickness of the resonant cavity is designed to be less than three halves of the lasing wavelength to increase the relaxation oscillation frequency of the semiconductor laser.

2. The semiconductor laser according to claim 1, characterized in that The thickness of the resonant cavity is between one lasing wavelength and three halves of the lasing wavelength; or The thickness of the resonant cavity is between one half of the lasing wavelength and one lasing wavelength; or The thickness of the resonant cavity is less than or equal to one half of the lasing wavelength.

3. The semiconductor laser according to claim 1, characterized in that, The multi-quantum well structure includes a plurality of overlapping well layers and barrier layers, and the strain modes and / or strain amounts of the well layers and barrier layers are not exactly the same.

4. The semiconductor laser according to claim 3, characterized in that, The strain modes of at least some adjacent well layers and barrier layers are different; or The strain modes of at least some adjacent well layers and barrier layers are the same.

5. The semiconductor laser according to claim 3, characterized in that, The strain amounts of at least some adjacent well layers and barrier layers are different; or The strain amounts of at least some adjacent well layers and barrier layers are the same.

6. The semiconductor laser according to claim 3, characterized in that, In the direction close to the top mirror structure, the strain amount of at least some well layers changes stepwise; or The strain amount of at least some barrier layers changes stepwise.

7. The semiconductor laser according to claim 3, wherein In the direction close to the top mirror structure, the strain amount of at least some well layers changes in an arithmetic progression; or The strain amount of at least some barrier layers changes in an arithmetic progression.

8. The semiconductor laser according to claim 3, characterized in that, In the direction close to the top mirror structure, the strain amount of at least some well layers changes in a geometric progression; or The strain amount of at least some barrier layers changes in a geometric progression.

9. The semiconductor laser according to claim 3, characterized in that, In the direction close to the top mirror structure, the strain modes of at least some well layers are the same; or The strain modes of at least some barrier layers are the same.

10. The semiconductor laser according to claim 3, characterized in that, The strain mode includes any one of compressive strain, tensile strain, and no strain.

11. The semiconductor laser according to claim 3, wherein, The strain amount is between 0.03% and 12%.

12. The semiconductor laser according to claim 1, wherein The multi-quantum well structure includes a plurality of overlapping well layers and barrier layers, at least one well layer in the well layers is a compressive strain well layer, and the indium component content in the compressive strain well layer is 0.

12.

13. The semiconductor laser according to claim 12, characterized in that, The well layers and barrier layers are made of InGaAs and AlGaAs materials respectively.

14. The semiconductor laser according to claim 1, wherein, Further comprising: An oxide confinement layer formed in the top mirror structure, the oxide confinement layer is disposed adjacent to the resonant cavity, and the oxide confinement layer is used to define the light emitting region of the semiconductor laser.

15. An optical emission component, characterized in that, The light emitting component includes the semiconductor laser according to any one of claims 1-14.

16. An optical module, characterized in that, Including a light emitting module and a light receiving module, and the light emitting module uses the light emitting component according to claim 15.

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